1. Field
The presently disclosed embodiment relates to the general field of ultrasonic inspection of the manufacturing quality of aeronautical system parts, especially composite parts, and more particularly to the inspection of the material health of such parts by laser-ultrasound.
2. Brief Description of Related Developments
The analysis of the material health of structural elements is at the present time carried out by laser-ultrasound, which is a contactless inspection method that is very suitable for parts of complex shape.
It will be recalled here that analysis of material health consists in searching for defects, delaminations, shrink marks, pores, cracks or other anomalies that may be found in materials used to manufacture mechanical parts, especially structural elements.
To meet the need for high-throughput inspection of parts, the current tendency is to entrust the execution of integrity tests to automatic systems, in other words robots. The execution of these tests by robots especially makes it possible, in the context of tests on mass-produced parts, to ensure an excellent reproducibility of the tests from one part to the next.
From a structural point of view, these robots are generally equipped with an arm, or more generally a movable appendage, terminating in a laser source. Especially in the case of inspection of large parts, these robots may furthermore be configured so as to be able to move so as to position themselves in proximity to the part.
In certain existing installations, the parts to be inspected are held stationary during the inspection. The robot moves the inspecting head over the part, and hence it is the inspecting head, and not the part, that moves. This is in particular the case for installations intended to test large parts.
Depending on the circumstances, the laser source may then be a stationary beam source, the integrity test then being carried out by moving the inspecting head so that it illuminates in succession a set of points distributed over the surface of the part that it is desired to inspect. In such a configuration, the part is inspected by operating the robot in a dynamic mode. The surface is thus scanned by moving the robot, or at least the inspecting head, relative to the surface to be inspected.
Alternatively, the laser source may also be a moving beam source. In this second case, the source is itself equipped with optical means, mirrors for example, allowing, to a certain extent, the laser beam produced to be deflected about one or two axes. Thus, the integrity test is carried out by positioning the source in succession facing the part at various points that are spaced apart from each other, and by scanning a surface portion with the laser beam emitted by the source so that said beam covers a given zone of the surface of the part. The number and arrangement of the inspection points are defined such that during the test the entirety of the surface of the part is scanned by the laser beam. Such a configuration is especially used in the LUCIE (acronym of “Laser Ultrasonics Composite inspection Equipment”) system developed by the Applicant.
In contrast, in other existing installations the robot includes a stationary inspecting head with a stationary laser beam source and it is the parts to be inspected that are moved and passed in front of the inspecting head. It is then the movement of the inspected part that makes it possible for the inspecting head to scan the entire surface of the part. In such installations the part may for example be moved by a handling arm that picks up the part and moves it facing the inspecting head. Such installations have the advantage of being simple and robust, insofar as, since the inspecting head remains stationary, it is easier to supply the laser source with power than would be the case if the same source were mobile. The handling arm here serves only to move the inspected part. This simplicity is moreover amplified if the laser source used emits a stationary beam. In contrast, to inspect the entirety of the part the handling arm must be able to precisely position the part relative to the inspecting head, and be able to rapidly more the latter.
Although these two types of installation are generally very suitable for the type of integrity inspections currently carried out by robots, there are however cases where they lead to limitations, especially in terms of the rapidity of inspection execution or even in terms of the effectiveness of the tests performed. In particular, such installations are generally not very appropriate for the inspection of the integrity parts having irregular surfaces, with more or less marked reliefs, and/or a complex geometry.